Satish Lele

Tank Farm
  • Storage Tanks: A storage tank is a container, usually for holding liquids, sometimes for compressed gases, called as gas tank. The term is used for manufactured containers. Storage tanks operate under no or very little pressure, distinguishing them from pressure vessels. Storage tanks are often cylindrical in shape, perpendicular to the ground with flat bottoms, and a fixed or floating roof. There are usually many environmental regulations applied to the design and operation of storage tanks, often depending on the nature of the fluid contained within. Above ground storage tanks differ from underground storage tanks in the kinds of regulations that are applied. Storage tanks are available in many shapes, vertical and horizontal cylindrical, open top and closed top, flat bottom, cone bottom, sloping bottom and dish bottom. Large tanks tend to be vertical cylindrical, or to have rounded corners with transition from vertical side wall to bottom profile, which makes it to easier withstand hydraulic pressure of contained liquid. Most container tanks for handling liquids during transportation are designed to handle varying degrees of pressure. A large storage tank is sometimes mounted on a lorry or on an articulated lorry trailer, which is then called a tanker.

    • Horizontal Drums: Horizontal vessels and drums are relatively large diameter cylindrical pressure vessels used for a variety of process functions. Their height above grade is usually determined by the Net Positive Suction Head requirements of the pumps in the liquid outlet line or the gravity flow requirements to other equipment. And they are supported by the use of saddles. Some vessels have Boots and Weirs. These accumulate water coming in the drum with hydrocarbons and water is drained out continuously or from time to time. Nozzle Orientation depends on the service. Inlets are from top. Outlets are from bottom and level gage is put on nozzles on side. Platforms are used to operate valves on top nozzles. Horizontal Drums are separated from each other by at least 4 feet or 1 meter and are located inside a dyke wall.
    • Vertical Tanks: Usually cylindrical they vary greatly in size from 2 feet to 200 feet diameter mostly flat bottomed with either an open or conical top, some of the large tanks used in refineries have a floating top where the roof floats on top of the liquid to eliminate vapor loss. Tank Roofs can be conical or dished. Flat roofs are not used. There are floating roofs for crude oil and gas storage. Small tanks are installed on concrete foundations while large tanks are placed on soil, called as mud foundation. Stairs and Ladders are provided to go up to the roof. Spiral stairs are provided for large diameter tanks while Ladders are provided for small diameter tanks. Large tanks are separated from each other by at least 20 feet or 5 meters and are located inside separate dyke walls. Small tanks are separated from each other by at least 4 feet or 1 meter and are located inside a common dyke wall. Dyke volume is designed to hold entire quantity of liquid inside the dyke wall, in case the tank ruptures. Fire Protection equipments are provided around the dyke wall. Offsite piping is generally mounted on grade. Tanks generally have inlet, outlet, recirculation and vent piping. Locate vertical vessels in the equipment rows on each side of the pipe way in a logical order based on the process and cost. The largest vessel in each equipment row should be used to set the centerline location of all vertical vessels in that equipment row. This largest vertical vessel should be set back from the pipe rack a distance that allows for pumps, the pump piping, an operation aisle between the pump piping and any piping in front of the vessel, the edge of the vessel foundation and half the diameter of this the largest vessel. Provide a clear access area at grade for vessels with removable internals or for vessels requiring loading and unloading of catalyst or packing. Provide vessel davits for handling items such as internals and relief valves on vessels exceeding a height of 30 feet or 9 meters above the high point of the finished surface, and on vessels not accessible by mobile crane. Orient davits to allow the lowering of appurtenances into the access area.
    • Pressure Vessels: A pressure vessel is a closed container designed to hold gases or liquids at a pressure substantially different from the ambient pressure. Many of the reaction vessels are pressure vessels. These have jackets or limpet coils to circulate heating or cooling media. The contents of the vessel are mixed by agitators. The pressure differential is dangerous and many fatal accidents have occurred in the history of their development and operation. Consequently, their design, manufacture, and operation are regulated by engineering authorities backed up by laws, such as ASME Section 8. For these reasons, the definition of a pressure vessel varies from country to country, but involves parameters such as maximum safe operating pressure and temperature. Pressure vessels are used in a variety of applications in both industry and the private sector. They appear in these sectors as industrial compressed air receivers and domestic hot water storage tanks. Other examples of pressure vessels are: diving cylinder, recompression chamber, distillation towers, autoclaves and many other vessels in mining or oil refineries and petrochemical plants, nuclear reactor vessel, habitat of a space ship, habitat of a submarine, pneumatic reservoir, hydraulic reservoir under pressure, rail vehicle airbrake reservoir, road vehicle airbrake reservoir and storage vessels for liquefied gases such as ammonia, chlorine, propane, butane. Pressure vessels may theoretically be almost any shape, but shapes made of sections of spheres, cylinders, and cones are usually employed. A common design is a cylinder with hemispherical end caps called heads. More complicated shapes have historically been much harder to analyze for safe operation and are usually far more difficult to construct.

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